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Engine dying..

RE: "Somewhat related, sometimes under very light acceleration it'll just go dead rich and stay that way until I lift off or give it more gas."

O2 & AMM sensors affect fuel stoic. If no intake air leaks, AMM might be a suspect.

>idling down problem is much improved

ECU re-evaluates its map data; on older GM ECUs, it takes drive-time to change stored data points.

Belt Timing - I'll assume crank, cam, and distributor are in sync.
 
Unplugging the o2 just made it run a tiny bit leaner.

Sidebar Footnote - On my LH 2.4 NA, the amber emission light is on, and mouse/rat chewed up wires to diagnostic test box. I assume O2 sensor is shot.

I'm using different injectors than OEM, Bosch 0 280 155 746, which have a slightly higher flow rate than OEMs.

Interesting, mpg is good, and tailpipe is clean/dry looking, which means not a rich mixture.

So, I plan not to fix diagnostic test box currently....engine starts and runs fine.
 
So brand new Bosch o2 and temp sensors changed nothing which is pretty much what I expected. Out of ideas.. It's like it has a boost leak except there aren't any. I found a pretty significant leak the first time I checked but fixing it made almost no difference.. I even filled my intercooler with water to see if there were any holes. I'm kinda surprised there weren't even any pinholes after being in that wreck. Also fixed an exhaust leak before the o2 sensors which did nothing.

ECU re-evaluates its map data; on older GM ECUs, it takes drive-time to change stored data points.

LH2.2 does none of that. In my experience it either works fine or something is wrong. I'm just having a really hard time figuring out what's wrong now.. It ran great with the new turbo for like 2 days before this garbage started happening.
 
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...nothing ....RE: "Somewhat related, sometimes under very light acceleration it'll just go dead rich and stay that way until I lift off or give it more gas."

O2 & AMM sensors affect fuel stoic. If no intake air leaks, AMM might be a suspect.

I have no idea how Bosch's ECU processes inputs...is AMM its first priority, or O2.

On earlier GMs, fluctuating richness (seen via O2) was not instantly corrected.
 
I assume your brake booster if fit for duty...removing its hose from intake and plugging intake vacuum port eliminates this possibility.
 
I'm fairly confident my MAF isn't the problem..

nhzD1kLh.jpg


I also swapped MAFs with my n/a 240 which runs perfectly with either MAF installed.
 
MAF isn't the problem...RE: "Somewhat related, sometimes under very light acceleration it'll just go dead rich and stay that way until I lift off or give it more gas."

1. Remove TPS connector

2. JB weld that wastegate closed so it doesn't move

3. Check brake booster fitness.
 
Well now it won't even start. Has spark, has injector pulse, fuel pump is turning on with cranking.

Fun.

Also I tried driving with the TPS disconnected days ago. All it did was make it idle worse. Still set correctly.
 
So.. I took out the intake pipe from MAF to airbox and that seems to have, at least mostly, fixed my problem. I don't know why. I've been using the same intake setup since I put the engine in this car. Sounds sweet tho.

jmRFDsmh.jpg
 
Maybe the MAF is getting too hot being that close to the exhaust?
Maybe CBV is recirculating at idle a bit and causing some reversion into the MAF?

Try moving the MAF up to the fender area like a 740/940 turbo.
 
same intake setup

I suspect air density, intake pipe, or a turbo glitch is related...if not turbo or intake pipe, with variations in air temperatures passing thru AMM, this might explain this: "...under very light acceleration it'll just go dead rich and stay that way until I lift off or give it more gas."


If engine ran fine in colder months, then I would suggest wrapping AMM and intake-pipe with high-temp Aerogel from Amazon URL I cited above.
 
I suspect air density, intake pipe, or a turbo glitch is related...if not turbo or intake pipe, with variations in air temperatures passing thru AMM, this might explain this: "...under very light acceleration it'll just go dead rich and stay that way until I lift off or give it more gas."


If engine ran fine in colder months, then I would suggest wrapping AMM and intake-pipe with high-temp Aerogel from Amazon URL I cited above.

I think you're right. Thanks for the help.

So I set this up:

fs7ahfTh.jpg


Ran nearly perfect with the upper MAF plugged in, not so great with the lower MAF. Upper MAF idles perfect, though it still goes rich sometimes, but not bad enough for the engine to sputter and spew smoke. Lower MAF has the going pig rich and crappy idle problems.

Switched em around and got the same result. Wanted an air filter so I found my old pod filter setup and put that in for now. Eventually I'll get some tubing and make a new pipe to use the airbox with the MAF up by the coolant bottle or something.

Cml6nBzh.jpg
 
Air density will change as a function of temperature changes....regardless of which AMM position is used, I would wrap with high-temp Aerogel on intake side there where high engine heat exists. Turbo will boost better with cooler air.

AMM apparently needs a constant air density....which would exist under OEM designed setup.
 
I'm wondering why I never had a problem using the MAF directly in front of the turbo until I put the new TD05 in.. Something about how smooth the airflow is or something. Anyway, it runs good so I'm happy.
 


Stuart Hilborn (9 October 1917 ? 16 December 2013)...automotive engineer...sell his injection systems to the public, which became popular with the hot rodders of the 1950s and 1960s....A classic mechanical Hilborn injection system is recognizable by its distinctive flared velocity stack intake pipes, rising straight up from each cylinder, flared at the open top, and usually polished or plated for a bright, shiny finish.

I don't think Cwazywazy is using SU carbs....
 
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